High energy centrifuge drive



Aug. 3, 1966 K. c. DRONE ETAL 3,267,768

HIGH ENERGY CENTRIFUGE DRIVE Filed July 23, 1962 6 Sheets-Sheet l BY muw A 7'702/VE V1 23, 1966 K. c. DRONE ETAL. 3,267,768

HIGH ENERGY CENTRIFUGE DRIVE Filed July 23, 1962 6 Sheets-Sheet 5 K/NGJZEV 6. PZO/VE #0144480 J. 5475) /A/V C 556'6' INVENTORJ' A T70WEYJ 3, 1966 K. c. DRONE ETAL 3,267,768

HIGH ENERGY CENTRIFUGE DRIVE Filed July 23, 1962 6 Sheets-Sheet 4 ,Z/A/GIZE) 6'. 020/145 MN 6'. EE

INVENTORS 1966 K. c. DRONE ETAL 3,267,768

HIGH ENERGY CENTRIFUGE DRIVE Filed July 25, 1962 6 Sheets-Sheet 5 K. C. DRONE ETAL HIGH ENERGY CENTRIFUGE DRIVE Aug. 23, 1966 6 Sheets-Sheet 6 Filed July 23, 1962 g 3,2517% Ice Patented August 23, 1966 3,267,768 HIGH ENERGY CENTRHIFUGE DRIVE Kingsley C. Drone, Orinda, Howard J. Bates, Walnut Creek, and Ian C. Begg, Urinda, Califi, assignors to The Rucker Company, a corporation Fiied July 23, 1962, Ser. No. 211,818 6 Claims. (Cl. 74-572) In recent years there has come into existence a form of centrifuge especially used in testing specimens to observe their reactions under special conditions such as high acceleration and the like. This form of centrifuge comprises a central stand .or base on which a diametral arm is mounted for rotation about a vertical axis. A suitable mount or support for a test specimen is provided at the outboard end of the arm. Centrifuges of this sort can be made large enough to accommodate a man as a test subject. Such a centrifuge correspondingly has a relatively great mass and a high inertia. Yet there has arisen a demand for such a testing device for use in observing effects due to relatively great onsets. Onset is defined as acceleration in a tangential direction. The requirement is for a centrifuge that can create acceleration onsets (at what is presently considered to be a very high rate) not only on the specimen being tested but also on the entire mass of the centrifuge arm. In one instance such arm has a radius of approximately fifty feet and is correspondingly massive.

It is therefore an object of the invention to provide a means for imparting a relatively rapid acceleration onset to a centrifuge.

Another object of the invention is to provide a device for imparting energy to a centrifuge at a' relatively high rate but without the necessity of extra large driving motors.

A still further object of the invention is to provide a high energy centrifuge drive capable of imparting large amounts of energy to the centrifuge or withdrawing large amounts of energy without excessive strain on the mechanism so that the energy transfer can be repeated indefinitely.

Another object of the invention is to provide a high energy centrifuge drive in which coupling and decoupling between the centrifuge arm and the driving and retarding mechanisms can be readily controlled with initially small forces.

A still further object of the invention is to provide a means for maintaining a centrifuge in operation at the desired rotational rate or velocity within a small range of variation.

Other objects together with the foregoing are attained in the embodiment of our invention described in the accompanying description and illustrated in the accompanying drawings, in which:

FIGURE 1 is a plan of a centrifuge constructed purw suant to the invention, a small portion of the structure being broken away to reduce the figure size.

FIGURE 2 is for the most part a side elevation of a centrifuge constructed pursuant to the invention, a portion of the showing being in cross section on a vertical plane and a portion of the structure being broken away to reduce the figure size.

FIGURE 3 is a view of the centrifuge base portion. The View on the left of the central axis is an elevation of part of the base mechanism with its appurtenances, whereas the view on the right of the central axis is a cross section on a vertical axial plane.

FIGURE 4 is a cross section on a vertical axial plane through part of a brake mechanism.

FIGURE 5 is a cross section on a vertical axial plane through a clutch mechanism and its attendant devices. FIGURE 6 is a diagram illustrating the interconnection of various controlling instrumentalities for the high energy centrifuge drive.

Pursuant to the invention, one embodiment of the centrifuge is installed in a building having a floor 5 and an excavated support arrangement 6. The centrifuge structure includes a machine frame 7 or base generally circular in contour and symmetrical about a central rotational axis 8 disposed vertically. The base is provided with suitable supporting mechanism to hold a centrifuge arm 9 extending radially in both directions on opposite sides of the axis. The arm terminates at one end to serve as a counterweight and is bifurcated at the other end to afford a yoke 11 supporting bearings 12 and 13 in which a gimbal ring 14 is disposed for rotation about a vertical axis. Similar bearing structures 16 on the gimbal ring 14 serve to support a specimen and test chamber 17 for rotation about a horizontal axis. With this arrangement the centrifuge arm 9 rotates about the vertical axis 8, the gimbal ring 14 can swing about a parallel vertical axis and the specimen chamber 17 can be swung or rotated about a horizontal axis located in a plane normal to the axis 8.

In an exemplary operation of the structure, the chamber 17 and its contained specimen are given a high (positive) acceleration from (say) a standing start to a high angular velocity or are slowed (negatively accelerated) from a high velocity to (say) stopped condition. As another example, the chamber and the specimen are rotated at substantially a constant speed or angular velocity about the axis 8.

Disposed in a suitable portion of the base 7 is a supporting frame member 21 (FIG. 3) arranged symmetrically about the axis 8 and serving to support a lower radial and thrust bearing 22. This conveniently is a ball or other antifriction bearing of a diameter to have its outer race suitably seated in the frame member 21 and to have its inner race appropriately engaged with a drive tube 23. Also provided is another antifriction bearing 24 effective primarily as a radial bearing. The inner race of the bearing 24 engages the periphery of the drive tube 23 and the outer race is suitably supported in a part 26 of the main frame 7 of the machine.

With this arrangement the drive tube 23 is readily rotatable about the axis 8 and is supported and located by the antifriction bearings 22 and 24. Appropriate supply and return lubricant conduits 27 and 28 are provided to keep the bearings well oiled and sufficiently cool. The centrifuge arm 9 is secured by appropriate fastenings (not shown) to the inturned upper end of the drive tube 23 so that the arm and the drive tube rotate together as a single body.

For some operating conditions, particularly when only relatively low rates of acceleration changes or steady speed are requisite in rotating the centrifuge, means are provided for imparting rotational force thereto. Disposed on an extension around the drive tube in the upper portion thereof is a ring gear 31 concentric with the axis 8. Engaging the ring gear at appropriate intervals around its periphery is a plurality of spur drive gears 32, each of which is driven by a pair of hydraulic motors 33 and 34. These motors are supplied with oil through appropriate ducts 36 joined to a manifold 37 beneath the floor 5 and the return oil is carried through ducts 38 extending to a return manifold 39. The supply manifold 37 is connected to an appropriate source of hydraulic fluid under pressure (not shown). When the source supplies pressure fluid, some or all of the hydraulic motors 33 and 34 are operated separately or in unison to turn the spur drive gears 32 and the ring gear 31 and so rotate the drive tube 23 and the arm 9.

It is not feasible to provide enough power through the various motors 33 and 34 to get the very high amounts of acceleration sometimes desired. Consequently, and in accordance with this invention, wve preferably PI'OlVidE on the frame 7 a flywheel 41 of considerable mass. The flywheel has most of its mass concentrated in its rim 42 in the customary way, and also has a central web 43. The flywheel is maintained in concentric relationship with the drive tube 23, that is to say, concentrically with the axis 8, by means of a radial antifriction bearing 44 interposed between an extension 46 of the flywheel structure and a cone 47 forming part of the base frame 7. The bearing 44 serves primarily only as a radial bearing, although in emergencies and for short periods it can take suflicient axial thrust to hold the flywheel in proper vertical location. There is an adequate oil supply to the antifriction bearing 44 and a proper return through lubricant piping 49.

Under normal operation, the axial load or weight of the flywheel 41 is preferably taken by a hydrostatic bearing 51. This amounts to a ring made up of segments having hydraulically filled troughs. The bearing is of annular plan and is disposed on a shelf forming part of the frame 7 and very closely underlies a part of the lower face of the flywheel rim 42. A supply of hydraulic fluid under appropriate pressure arrives through ducting 52 and goes to the hydrostatic bearing 51 to support the flywheel axially. Overflow is removed through return piping 53. In operation, the quantity of hydraulic fluid under pressure arriving through the conduits 52 is suflicient despite clearance leakage to maintain a body of oil between the bearing 51 and the lower face of the flywheel rim 42. The flywheel, in effect, floats on oil. The interrelationship of the radial bearing 44 and of the hydrostatic bearing 51 is such that during normal rotation of the flywheel they operate in conjunction, the former as a radial locator and the latter as an axial locator. When the flywheel is stationary and there is no oil, as in shut-down, the flywheel Weight is well supported without overstressing the bearing 44. Even in operation, should the hydrostatic bearing 51 fail momentarily or completely, the antifriction bearing 44 is suflicient to prevent sudden accident or damage.

Pursuant to the invention, means are provided for imparting the desired rotational velocity to the flywheel 41 independently of the driving motors 3'3 and 34 of the drive tube 23. For that reason there is mounted on the flywheel 41, preferably on a hub extension 54 of the web 43, a driven annular gear 56 with which mesh a number of driving gears 57, each of which is propelled by a hydraulic motor 58. Piping 59 conducts hydraulic fluid under pressure to the various motors 58 in parallel, whereas the spent hydraulic fluid is returned through appropriate return ducting to the source of hydraulic pressure. in one instance, a battery of twelve of the hydraulic motors 58 is provided, the motors being disposed at appropriate intervals around the periphery of the gear 56. The aggregate power of all of the motors 58 is not sufiicient directly to impart the desired acceleration to the centrifuge. 'In practice, the motors are all operated for a substantial period of time until the fly wheel 41 comes up to the desired speed. In fact, the flywheel 41 is normally sped up to a value of angular velocity some- What in excess of the desired rotational speed of the centrifuge arm 9.

When the flywheel 41 has come up to the desired speed, it is put into driving engagement with the drive tube 23. As particularly illustrated in FIGURE 5, the hub 54 is a part of a tubular body 61 having an interior surface formed with a plurality of axially extending splines 62. Interengagin-g at their outer toothed peripheries with the splines are clutch drive plates 63. These plates are superposed and are peripherally rotated by the body 61 and flywheel. Each of the drive plates 63 rests upon and is axially positioned by a respective one of a plurality of of annular pneumatic tubes 64 each disposed between a 4 l lower supporting ring 66 and an upper supporting ring 67.

The mechanical construction of all of the supporting tubes 64 is identical so that a description of one applies equally to the others. The lowermost supporting tube 64 rests upon an extension 68 secured to the body 61. Supported on the lowermost clutch drive plate 63 is a similar pneumatic tube and so on until the entire group of clutch drive plates is supported. Each of the tubes 64 is provided with air under pressure, the pressure being sufficient normally to separate the superposed clutch drive plates 63. Since each plate rests on the one below it, the unit pressure in each one of the supporting tubes 64 is different, that in the lowest tube 64 being greatest and that in the upper tube 64 being least. Thus, when all of the supporting tubes 64 are properly inflated, the clutch drive plates 63 are spread apart.

Interspersed with the clutch drive plates 63 are clutch driven plates 71 located concentrically about the axis 8. Since the driven plates 71 are all alike, a description of one applies equally to the others. The driven plates 71 on their inner periphery are provided with teeth 72 interengaging with axially extending splines 73 formed as part of the drive tube 23. The lowermost driven plate 71 rests on an extension 74 of a hub 76 secured to the drive tube 23 and serves as a support for one of a plurality of inner penumatic tubes 77 similar to the outer pneumatic tubes 64. Each of the tubes 77 is similarly disposed between mounting plates 78 and 79. Also, like the outer tubes 64, the various pneumatic tubes 77 are each provided with a suitable connection 81 so that the unit pressure in each can be arranged at a desired value. These values decrease as the pneumatic tubes are located higher on the structure. The penumatic devices 64 and 77 urge the various, interspersed clutch drive and driven plates to separate from each other.

When the plates are separated, friction disks 82 seated in appropriate depressions in the driven plates are out of physical contact with the drive plates. Under these circumstances, the flywheel 41 rotates entirely independently of the drive tube 23. When the energy stored in the flywheel 41 is to be transferred to the drive tube 23, then the clutch is engaged. Usually an abrupt engagement is desired. Engagement is accomplished by inflation of a relatively large pneumatic tube 86 mounted between guide plates 87 and 88. The upper plate 87 bears against an extension 89 on the drive tube 23 and the lower plate 88 bears against the upper most driven plate 71. A pipe 90 connects through an appropriate one of a number of swivel joints 91 to a stationary source of pneumatic pressure and control.

When air pressure is admitted to and made effective upon the master tube 86, a superior force is exerted down- 'wardly to cause the driven disks to be brought into frictional engagement with the drive disks 63. When the superior force is great enough to prevent slip, the clutch is fully engaged. When the clutch is to be disengaged, the pressure within the master tube 86 is reduced or released and that within the tubes 64 and 77 becomes fully eifective so that the parts are fully restored to their frictionally separate, initial condition. When all of the tubes 64 and 77 as Well as the tube 86 are connected through swivel joints to controlled supply and exhaust of actuating fluid, it is possible to engage or disengage the clutch fully in a very short time. The flywheel as a unit can be almost instantaneously coupled with the drive tube 23 for large energy transfer or it is possible to provide any desired intermediate amount of friction. Energy can be transferred back and forth between the flywheel and the drive tube 23 in any desired and controlled way in order to maintain the desired acceleration or rotational velocity of the centrifuge arm 9.

It is also possible to reduce the rapidly rotating centrifuge arm to a stationary condition in a short time in order to afford a large negative acceleration or deceleration. That is accomplished by first releasing the clutch and then applying a friction brake. As particularly i1- lustrated in FIGURE 4, the brake is associated wit-h the drive tube 23 as well as with the frame 7. A bracket 92 upstanding from the frame has interior splines 93 engaging the toothed periphery of a number of stationary brake disks 94. Interspers'ed with these disks are rotary brake disks 96 on their interior periphery provided with teeth interengaging with axial splines 97 on the drive tube 23. The various stationary and rotary brake disks are individually supported by pneumatic tubes 98 and 99 similar to those previously described in connection with the clutch mechanism shown in FIG- URE 5. Individual pneumatic pipes 101 and 102 establish the desired pressure in each of the pneumatic tubes. The brake plates 94 are ultimately supported on an extension 103 of the frame 7, while the brake disks 96 are ultimately supported on an intermediate heat conducting spacer 104 resting on a flange 106 secured to the drive tube 23. The various disks 96 preferably are provided with appropriate recesses holding antifriction lining 107.

Normally, the air pressure within the pneumatic tubes 98 and 99 keeps the various brake plates separated and out of frictional contact. When, however, the brake is to be applied, air pressure is supplied through a line 108 to the interior of a master brake pneumatic tube 111 located between guide plates 112 and 113 and so exerting thrust against a part 114 of the frame and against the uppermost plate 96. The line 108 is connected to an appropriate control through a swivel joint (not shown). The superior force due to higher pressure within the tube 111 forces the various brake plates into frictional engagement to the desired extent and dissipates the rotational energy of the drive tube 23 and its attached parts in the form of heat. The rotational parts are brought to a standstill or are slowed to any desired degree.

While the centrifuge can be rotated in any desired way, it is often preferred to operate the centrifuge at a carefully regulated rate of rotation. For this reason, there is provided structure as shown in FIGURE 6 to bring about the desired functioning. A pressure fluid actuator 126, shown as a hydraulic cylinder, has a piston 127 therein mounted on a shaft 128. This actuator structure is a representational equivalent of or is comparable to the pneumatic chamber 86 shown in FIGURE 5. The actuator operates the clutch device to couple and uncouple the centrifuge rotor and the flywheel. The position of the actuator is dependent upon the operation of a servo valve 129 governing flow from both ends of the cylinder 126 to and from a hydraulic supply 131. To act as a control for the servo valve 129, the instantaneous or momentary rotational velocity of the rotor 9 is sensed by a follow pinion 132 in geared engagement therewith. This rotates a shaft 133 driving a tachometer 134 indicating the speed of the rotor. The rotation of the shaft 133 also serves as one input to a program receiving device 136. The desired program serves as a second input to the program receiving device 136 through an input path 137. The difference between the desired rotational performance as indicated at the input 137 and the actual rotational performance as indicated by the shaft 133 is represented by an appropriate signal on a path 138. The output signal is sent through the circuitry of a DC. amplifier 139 and the circuitry of a DC. integrator 141, the outputs therefrom being combined and supplied to a modulator 142. Conveniently this is an alternating current device supplied with a four hundred cycle per second current entering through a lead 143. The modulated signal then is transferred through an A.C. amplifier 144 into a demodulator 145 having a four hundred cycle per second supply 146 and affords an output signal on a path 147 for controlling the servo valve 129.

A feedback is provided from the actuator cylinder 126.

A differential pressure responsive device 148 is connected by ducts 149 and 151 to sense the pressure at the opposite ends of the actuator cylinder 126. The differential pressure device 148 is provided with a four hundred cycle per second current through a conductor 152. The output is transferred by a conductor 153 through an A.C. amplifier 154 to a conductor 156 merging with the output of the modulator 142. The difference between the signal from the modulator 142 and the feedback signal from the conductor 156 provides a resultant signal travelling through the amplifier 144 and the demodulator to control the servo valve 129. If desired, the brake (FIG. 4) can be controlled separately by a similar arrangement or the brake and clutch can be controlled together by a comparable combined arrangement.

What is claimed is:

1. A high energy centrifuge drive comprising a base, a drive shaft journalled on and rotatable relative to said base about a vertical axis, a centrifuge rotor arm fixed on said drive shaft, a flywheel journalled on and rotatable relative to said base about said axis, means for rotating said flywheel, a plurality of drive clutch plates surrounding and coupled to rotate with said drive shaft, said drive clutch plates being vertically stacked and axially movable on said drive shaft, a plurality of driven clutch plates coupled to rotate with said flywheel, said driven clutch plates being vertically stacked and axially movable on said drive shaft, said drive clutch plates and said driven clutch plates being interspersed, means for urging said drive clutch plates and said driven clutch plates apart against the force of gravity, superior means for urging said drive clutch plates and said driven clutch plates together, and means responsive to the speed of rotation of said drive shaft relative to said base for controlling the operation of said superior means.

2. A device as in claim 1 in which said drive plates and said driven plates are urged vertically apart by interposed pneumatic chambers.

3. A device as in claim 2 in which said interposed pneumatic chambers are maintained at successively higher pressures considered in a downward direction.

4. A high energy centrifuge drive comprising a base, a drive shaft journalled on and rotatable relative to said base about a vertical axis, a centrifuge rotor arm fixed on said drive shaft, a flywheel encompassing said drive shaft and located to rotate about said axis, a rim on said flywheel having a lower face normal to said axis, a hydrostatic bearing on said base engaging said face to support said flywheel, means for driving said flywheel, and an axially engageable clutch for coupling said flywheel and said drive shaft.

5. A high energy centrifuge drive comprising a base, a centrifuge rotor, means for mounting said centrifuge rotor on said base for rotation about a vertical axis, means for so rotating said centrifuge rotor, a flywheel having a rim with a horizontal surface, a bearing for mounting said flywheel on said base concentric with said centrifuge rotor, a hydrostatic bearing engaging said horizontal surface for supporting said flywheel rim on said base, means for coupling and uncoupling said flywheel and said centrifuge rotor, and means for driving said flywheel.

6. A high energy centrifuge drive comprising a base, a drive tube, means for mounting said drive tube on said base for relative rotation about a vertical axis, a centrifuge arm on said drive tube, an antifriction bearing on said base concentric with said axis, a flywheel having a web and a rim, means for connecting said web to said antifriction bearing to support said flywheel for rotation about said axis, a hydrostatic bearing on said base concentric with said axis and engaging said rim and also to support said flywheel for rotation about said axis, means for coupling said flywheel and said drive tube, and means for rotating said flywheel.

(References on following page) References Cited by the Examiner UNITED STATES PATENTS Roche 192103 King 308-9 5 Hughes 73-1 Grant 192-88 FRED C. MATTERN, JR., Primary Exz zminer.

BROUGHTON DURHAM, Examiner. W. S. RATLIFF, JR., Assistant Examiner. 

1. A HIGH ENERGY CENTRIFUGE DRIVE COMPRISING A BASE, A DRIVE SHAFT JOURNALLED ON AND ROTATABLE RELATIVE TO SAID BASE ABOUT A VERTICAL AXIS, A CENTRIFUGE ROTOR ARM FIXED ON SAID DRIVE SHAFT, A FLYWHEEL JOURNALLED ON AND ROTATABLE RELATIVE TO SAID BASE ABOUT SAID AXIS, MEANS FOR ROTATING SAID FLYWHEEL, A PLURALITY OF DRIVE CLUTCH PLATES SURROUNDING AND COUPLED TO ROTATE WITH SAID DRIVE SHAFT, SAID DRIVE CLUTCH PLATES BEING VERTICALLY STACKED AND AXIALLY MOVABLE ON SAID DRIVE SHAFT, A PLURALITY OF DRIVEN CLUTCH PLATES COUPLED TO ROTATE WITH SAID FLYWHEEL, SAID DRIVEN CLUTCH PLATES BEING VERTICALLY STACKED AND AXIALLY MOVABLE ON SAID DRIVE SHAFT, SAID DRIVE CLUTCH PLATES AND SAID DRIVEN CLUTCH PLATES BEING INTERSPERSED, MEANS FOR URGING SAID DRIVE CLUTCH PLATES AND SAID DRIVEN CLUTCH PLATES APART AGAINST THE FORCE OF GRAVITY, SUPERIOR MEANS FOR URGING SAID DRIVE CLUTCH PLATES AND SAID DRIVEN CLUTCH PLATES TOGETHER, AND MEANS RESPONSIVE TO THE SPEED OF ROTATION OF SAID DRIVE SHAFT RELATIVE TO SAID BASE FOR CONTROLLING THE OPERATION OF SAID SUPERIOR MEANS. 